Mayonnaise is a well recognized oil-in-water emulsion. The manufacture of mayonnaise in the United States is controlled by the Food and Drug Administration (FDA) Standards of Identity. Mayonnaise is the emulsified semi-solid, non-pourable, oil-in-water emulsion prepared from vegetable oil, water, egg yolk-containing material, and acidifying ingredient. To be called a mayonnaise product in accordance with the FDA Standards of Identity, the emulsified dressing must be emulsified with egg yolk as the sole emulsifier and must contain at least 65 weight percent vegetable oil.
In the basic method for the production of mayonnaise, the required ingredients are assembled and premixed in a container. The resulting mixture is transferred to an emulsifying apparatus such as a colloid mill. A colloid mill provides relatively high shear forces which finely divides the mixed ingredients and forms a highly viscous oil-in-water emulsion. High viscosity is a desirable quality because it produces a high level of stability.
In a typical mayonnaise emulsion, the high viscosity is a result of tightly packing the globules of the dispersed phase (i.e., oil globules) in the continuous water phase. This is relatively easy to accomplish when the percentage of oil is greater than 74 weight percent. Thus most commercial mayonnaise products typically have oil contents much higher than the legal minimum 65 weight percent (i.e., an oil level greater than about 74 weight percent). It is generally difficult to reduce the oil level of such a mayonnaise product to below about 74 weight percent and still achieve a stable oil-in-water emulsion. Numerous approaches for preparing such low oil-level mayonnaise type products have been used. For example, Schoenberg, U.S. Pat. No. 4,923,707, describes a method for producing a mayonnaise wherein the oil content can be reduced to levels of about 65 to 72 percent using a corn syrup with a low DE of about 27 to 43 in the mayonnaise formulation.
It has been recognized for some time that oil-in-water emulsions having oil contents less than 65 weight percent could be produced with greater stability using a starch base. The term "salad dressing" refers to such starch-containing emulsions. Salad dressing, as generally defined in the FDA Standards of Identity, is an emulsified semi-solid, non-pourable oil-in-water emulsion prepared from an edible vegetable oil, an acidifying ingredient selected from vinegar, lemon juice, and lime juice, an egg yolk-containing ingredient, and a cooked or partially cooked starch paste prepared from food starch, tapioca flour, wheat flour, rye flour, or mixtures of these starchy materials and water. Salad dressing may also contain optional thickening agents (in addition to the egg yolk) such as, for example, gum acacia, carob bean gum, guar gum, gum karaya, gum tragacanth, carrageenan, pectin, xanthan, propylene glycol alginate, sodium carboxymethyl cellulose, and mixtures thereof. Salad dressing, as defined by the FDA Standards of Identity, contains at least 30 weight percent by weight of vegetable oil and sufficient egg-yolk containing ingredient to provide egg yolk solids equivalent to that provided by liquid egg yolk at a least 4 weight percent by weight.
While salad dressing products are useful to those wishing or needing to restrict their intake of calories, such products still contain significant levels of calories and oil. Thus, it would be desirable to further reduce the level of vegetable oil in such products, while at the same time maintaining the desired consistency, and texture. One approach for preparing such low-calorie mayonnaise and salad dressing has been to use polyol fatty acid polyesters, which are well known fat substitutes, in place of the normal triglyceride oils. For example, Mattson et al., U.S. Pat. No. 3,600,186, discloses low-calorie food compositions, including mayonnaise and salad dressing products, wherein at least a portion of the fat is replaced with certain nonabsorbable, nondigestible polyol fatty acid polyesters. These polyol fatty acid polyesters are typically formed by esterifying sugars or sugar alcohols having from 4 to 8 hydroxy groups with fatty acids having from 8 to 22 carbon atoms. At least four of these hydroxy groups are esterified with the fatty acids in order to make the resulting sugar or sugar alcohol fatty acid polyesters nonabsorbable and nondigestible. More recently, European Patent Publication 0 375 239 A2 (Jun. 27, 1990), described emulsified oil dressing products containing blends of polyol fatty acid polyesters and triglyceride oil.
In both these references (Mattson et al. and the European publication), the emulsified oil dressings were prepared using conventional mayonnaise-and salad dressing-making techniques wherein the polyol fatty acid polyesters was simply and directly substituted for the triglyceride oil used in conventional dressing products. But such methods (i.e., a direct substitution of the polyol fatty acid polyester for the triglyceride oil) tend to produce unstable emulsion products. Such direct substitution generally produces an unstable oil-in-water emulsion which tends, upon storage, to invert to an oil-continuous emulsion or to separate into oil and water phases. Such unstable emulsions would clearly not be acceptable commercially. In some case, such a direct substitution using conventional processing techniques does not even produce the desired initial oil-in-water emulsion.
It would be desirable therefore to provide a method of making polyol fatty acid polyester-containing mayonnaise and salad dressing products which have reduced calorie content, good flavor, consistency, and mouthfeel, and which are stable. The present invention provides such a method. In one embodiment of the present invention, a method is provided for producing stable mayonnaise-type, semi-solid dressings utilizing polyol fatty acid polyesters as the fat component. In another embodiment of the present invention, a method is provided for producing stable semi-solid salad dressing type products which have a starch base associated with salad dressing, but which have polyol fatty acid polyesters as the fat component. In still another embodiment of the present invention, a method is provided for producing stable pourable dressings utilizing polyol fatty acid polyesters as the fat component. The polyol fatty acid polyester-containing emulsified dressings prepared by the method of this invention are stable (i.e., the oil-in-water emulsion has a significantly reduced tendency to invert or to phase separate).